Figure



March 10, 1964 T.v.TUB1EL|.- w1cz ETAL 3,124,796

ARMAMENT EVALUATOR Filed Jan. 19, 1959 2 Sheets-Sheet l Hoy 5. Fredr/'c/ron, Thaddeus M Tub/e/eW/CZ,

77h e fr' A ttor/veg.

March 10, 1954 T. v. TUBlELEwlcz ETAL 3,124,796

ARMAMENT EvALUAToR Filed Jan. 19, 1959 2 Sheets-Sheet 2 fn Ver? torus.' Hoy 5. F'redf/c/fso, Thaddeus V. Tub/'e/eW/cz,

' The/'r' Attorney United States Patent Oil-ice 3,124,796 IAMENT EVALUATOR Thaddeus V. Tuhielewicz, New York, and Roy B. Fredricltson, Kirkwood, N.Y., assignors to General Electric Company, a corporation of New York Filed lan. 19, 1959, Ser. No. 787,513 1 Claim. (Cl. 343-7) This invention relates to re control systems and more particularly to an armament evaluator means for evaluating the dynamic accuracy with which the lire control system can lire on a real target in space.

Fire control systems which will utilize the armament evaluator of this application are generally comprised of a target detecting and locating device such as radar or the like which radiates impulses into space and receives rellected impulses or echoes back by means of reflection from objects Within the directional pattern of energy propagated by the radar antenna. The reiiected impulses from a desired target may be selected and from these impulses the range and position of the target may be determined. This data is then utilized by suitable computers and servo mechanisms to position the gun to fire projectiles at the selected target. Because the path of these projectiles does not follow a straight line, but rather follows variable ballistic trajectories, aifected by temperature, pressure, Wind velocity, vibration of the aircraft and various other factors, corrections are added to the position of the gun by means of a computer mechanism to compensate for these variables so that the gun axis is deliberately displaced from the radar line of sight `to the target to insure that the ballistic trajectory of a projectile will pass through the target location.

A means for harmonizing the tire control system in which the positioning of the turret and gun is harmonized with the target tracking device, such as radar antenna, to insure that the projectile tired from the gun will hit the target being tracked by the antenna has been disclosed and claimed in a co-pending patent application, Serial No. 745,770, filed June 30, 1958, in the name of Allen D. French, and assigned to the same assignee as the present invention. The above noted pending patent application adequately discloses a harmonizing means for a fire control system. However, in addition to har- Vmonizing the gun and target tracking device of a re control antenna, it is necessary to evaluate the in-flight performance or the dynamic operation of a lire control system. That is, it is desirable to be able to dynamically evaluate an airborne hre control system during in-liight use by the actual testing of the entire operation of the fire control system from the tracking of a target to the tiring of the gun and the projectile hitting the target. The only present known way of so evaluating present day lire control systems is by means of towed sleeves or drone targets, whereby the sleeve or drone is the target which is tracked by the antenna of the tire control system and the system is operated so that at the proper moment the gun is red to destroy the target. Gbviously, if the target is destroyed then it is known that the system is functioning correctly. However, if the target is missed there is no method of determining the closeness with which the projectile passed the target to thereby determine the necessary corrections to be made to the hre control system. As will be Well understood, the use of towed sleeves or drones requires extensive supporting and maintenance personnel, and the use of expensive equipment which, if the gun is adequately harmonized with the antenna of the fire control system, will of course, be destroyed. Therefore, it can be seen that there is a present need for obtaining a method of correctly evaluating the operation of fire control systems which will be readily useable by the operator of the re control system 3,124,796 Patented Mar. 10, 1964 or the pilot of the plane on which such fire control system is mounted, and which Will be relatively inexpensive and frequently useable, while at the saine time providing completely accurate evaluation of the operation of the fire control system.

As will be understood, the extreme complexity of lire control systems requires a great deal of maintenance to insure the correct operation and functioning of all the many components of such system. It is desirable that an evaluator means be provided whereby the fire control system could be operated frequently and inexpensively to determine the necessity for maintenance. By the use of such evaluating means maintenance personnel could readily establish the quantity and frequency of maintenance which is required for maintaining the operational status of any given type of lire control system.

lln providing such an evaluating means of fire control systems, it is desired to provide a permanent record of the action of the system whereby the maintenance personnel will be enabled to check the operation of the system from the tracking of a target to the tiring of the projectile and the passage of the projectile through the target area. A record of the evaluation of the action of the lire control systems through its entire operation would also provide the aerial gunners with a means of checking their methods of operating the fire control system t0 determine whether they are operating such systems correctly and also to provide assurance that the system will perform its required function.

It is accordingly one object of this invention to provide a means for evaluating the in-flight performance of a re control system during dynamic operation of such system.

Another object of this invention is to provide a means for evaluating the dynamic performance of a lire control system and providing a permanent record of such evaluation to enable maintenance personnel to'determine the adequacy of operation of such lire control systems.

A further object of this invention is to provide an evaluating means for a lire control system with a record of the dynamic operation of such system which is relatively inexpensive and may be added to present day fire control systems without altering the over-all operation of the iire control system.

A still further object of this invention is to provide a means for dynamically evaluating the in-ight preformance of a fire control system which may be readily added to present day lire control systems to obtain evaluation of the operation of such system at any time desired by the operator of such system,

In carrying out this invention in one form an evaluator device is provided electrically connected with a fire control system, the evaluator device having means for operating the antenna of such system for simulating the tracking of a target and to provide a simulated target range voltage to the range tracking circuitry of the ire control system, The evaluator device is designed to re the gun of the fire control system when the simulated target is at the correct range for scoring a hit, and for obtaining an indication of the closeness of the path of the fired projectile to the area in space Where the simulated target would be located. A recorder device is also provided to permanently record the information necessary to perform the desired evaluation of the operation of the system.

Further, in accordance with this invention the evaluator device may be incorporated within the lire control system itself or may be a light Weight unit which may be added to present day re control systems whereby the lire control systems may be dynamically evaluated under actual operating conditions.

This invention will be better understood and the manner in which its objects and advantages are obtained, by

a consideration of the following description taken in con-A junction with the accompanying drawings in which;

FIGURE l is a diagrammatic sketch, schematically illustrating the measured quantities of a fire control system;

FIGURE 2 is an electrical block diagram of a conventional re control system showing one form of connecting the evaluating device of this invention to the re control system;

FIGURE 3 is a schematic diagram of portions of the block diagnam shown in FIGURE 2 showing one form of some of the electrical circuits of the evaluating device of this invention and their connections with the fire control system.

Although the preferred embodiment of the present invention to be described is disclosed in connection with a gun fire control system `for aircraft employing radar tracking equipment, it is to be understood that this invention is not limited to either radar or to aircraft use, but may be employed with ground based installations or with land or sea going vehicles as well. The invention may also be combined with other types of target tracking equipment such as those using infrared or ultraviolet detector systems. It should also be understood that this invention is not limited to gun fired projectiles but may also be utilized in conjunction with rockets, missiles and the like.

Referring now to the drawings wherein like numerals are used to indicate like parts throughout and in particular with reference to FIGURE l, there is shown the tail portion of an aircraft, generally designated lil. The tail portion of the aircraft incorporates a fire control system comprising a radome l2 which encloses suitable impulse radiating elements and which is electrically connected to position a gun turret 14 housing a gun 16. In conventional systems of this type, the radar transmitter propagates a directional pattern of energy into space as is diagrammatically shown by the over-lapping loops 13 and Ztl symmetrically disposed about what is termed the radar line of sight or center line 22. Of course, it will be understood that while the overlapping loops 18 and 2@ are shown only in a horizontal direction these over-lapping loops radiate completely around the center line 22 somewhat in a form of a conical pattern. As is well known to those skilled in the art, by measuring the time for an echo or a reflected impulse to be received from a target and by noting the position of this echo within the directional pattern indicated by li and Ztl, the range and location of a target referenced to the center line 22 may be determined. This information can then be utilized through suitable computing networks to automatically position gun 16 in azimuth and elevation so that a projectile 24 fired by the gun would strike the indicated target. However, due to the ballistics trajectory and other factors determining the path 26 of the projectile 24, the axis of the gun 16 is not pointed directly at the target, but is deliberately misaligned therefrom so that the trajectory path 26 will intercept the target location. Under practical operating conditions many of the factors affecting the projectile path cannot be exactly measured. Therefore, despite the most accurate and expensive calibrations on the ground, generally termed harmonization, the actual projectiles fired in the air may miss the target by a considerable distance.

To reduce the time and cost of ground harmonization, as well as reducing the harmonization errors which occur during actual flight conditions, the invention disclosed in the aforementioned patent application, Serial No. 745,770, provides means for statically measuring a portion of the flight path of a test fired projectile, referenced to the center line of the radar, and thereafter employs this measurement to align or harmonize the gun and the radar. More specifically, in accordance with that invention, means are provided for setting up an area in space a known distance from the aircraft. This known space position is a portion of the total radar pattern and the radar equipment is focused on this position. The projectile 24 fired by the gun 16 will provide a reilected impulse or echo which will be noted by the radar thus informing the aerial gunner of the exact position of the projectile 24 as it passes through this known area in space. For example, consider the area designated by the lines 28 within the pattern indicated by the overlapping loops 18 and 26 at a given range Btl from the radome l2. It can be seen by the trajectory path 26 that the projectile 24 will pass somewhat beneath the radar center line 2,2.

Whereas the invention described in the aforementioned co-pending patent application provides a means for statically harmonizing the antenna and the gun during actual ight of the aircraft, it does not provide a desired dynamic evaluation of the fire control system since the antenna and turret are not operated in their track mode. For the operation of the invention of the aforementioned co-pending application, it is required that the turret be stowed and that various correction units be provided for correcting the position of the turret with reference to the position of the antenna. The present invention, which will now be described, provides a means for dynamically evaluating the over-all operation of the fire control system from the tracking of a simulated target, the firing of the gun, and the determination of the closeness of the path of the red projectile to the simulated target. Thus it will be readily apparent to those skilled in the art that the present invention is an improvement over the invention described and claimed in the co-pending patent application, providing the inventive concept of dynamically evaluating the operation of a re control system.

Referring now to FIGURE 2, there is shown a block diagram which represents a complete tire control system and showing one form of incorporating the present invention within such tire control system. As shown in FIG- URE 2, a radar antenna 4t) and its associated drive mechanism 42 is connected to a radar transmitter 44 by means of a wave guide or other type of transmission line 46 to propagate an electro-magnetic beam (not shown) into space and to receive a reflected electro-magnetic beam from any target located within the propagated beam. A gun turret 4S housing a gun Sil is interconnected by electronic and mechanical circuitry shown by the individually labeled blocks for measuring and controlling the position of the gun 50 to re projectiles at a target located by the radar beam.

Part of the re control system shown in block form in FIGURE 2 is a conventional fire control system and its operation is well known to those skilled in the art. Therefore, the operation of the conventional portion of this re control system will only be briefly discussed. As is well known, a trigger generator 52 is connected to a source of D.C. power 54 for providing trigger pulses which are utilized to operate modulator 56. The modulator in turn provides the necessary energy to operate the transmitter 44 which sends a pulse of RF energy through transmission line 46 to the antenna 4@ for radiation of an electro-magnetic beam into space. When a target is present capable of reecting energy, an RF pulse is reflected back to the antenna #itl and is carried back over a portion of transmission line 46, through a two-way switching device 58, as is well known to those skilled in the art, and over line to receiver 62. The receiver 62 is provided with conventional circuitry which converts the RF signal into a video pulse. This video pulse is fed over line 64 into the range tracking circuit 66, from which circuit, and other associated circuits, is derived the necessary information to properly position the fire control system on the target.

A range gate generator 68 develops a signal which is transmitted over line '70 and through line 72 to the range tracking circuit 66 to provide an early gate. The range gate generated signal is also transmitted over line 7() through a delay circuit 74 and through line 76 to the range tracking circuit 66 to develop a late gate. The early and late gates position themselves about the video pulse received from receiver 62, such that they track this video pulse whenever it changes its range in space. This range information is sent from the range tracking circuit 66 over line 78 to the range output cathode follower S0, and this range voltage is fed back over lines 82 and 84 to the range gate generator 68 so as to form a closed loop range servo. The range voltage is also fed from the range output cathode follower 80 over line 82 and line 86 to a computer 88 for inclusion in the ballistic computation for the positioning of the turret 48 and gun 50. As is well known in the art, the operation of the closed loop range servo is such that whenever the target changes its range the range gates automatically reposition themselves on the targets new location.

The gated Video signal, which is obtained from the range tracking circuit 66, in conjunction with the early and late gate, is fed over line 90 to the error signal circuit 92 where it is transformed into azimuth and elevation error signals. The azimuth and elevation error signals are fed over lines 94, 96 to antenna control amplifier 98. If antenna 40 is not pointed directly at the target, the antenna control amplier 98 will generate the necessary signals, which are fed over line 100, to drive the antenna drive mechanism 42 to position the antenna on the target. Once the antenna 40 is properly positioned on the target, the azimuth and elevation position information are sent from the antenna drive mechanism 42 over line 102 to the computer 88. In the computer 88, in conjunction with the range and environmental information, these signals are modified in accordance with ballistic equations and the corrected azimuth and elevational information is fed to the turret 48 over line 104. If the turret 48 is not positioned in accordance with the corrected azimuth and elevation signals, which are supplied from the computer 88, the turret servo amplifier 106 will be energized by these signals over line 108 to drive the turret 48 until it comes into correspondence with the position indicated by the azimuth and elevation signals. As is well known to those skilled in the art, when the turret is properly positioned on the target the gunner may fire on the target by actuation of firing button 110.

In order that the fire control system herein described may be provided with the desired armament flight evaluator means, such that the operation of the tire control system hereinbefore described may be evaluated by the simulation `of a target, the tracking of such target, the firing of the gun, and the determination of the path of the fired projectile in passing the simulated target, the various units noted in FIGURE 2 are incorporated into the tire control system. As shown in FIGURE 2, a programmer unit 112, a selector unit 114 and a recorder 1116, are connected into the fire control system. The various units include the necessary circuits to drive the fire control sys- ,tem through the desired stages of operation to satisfactorily accomplish evaluation -of the fire control system. As shown in FIGURE 2, the programmer unit 112 supplies two voltages to the range output cathode follower 80, a range voltage to the cathode of the range output cathode follower over the line 118 and a blocking voltage to the grid over line 120 to prevent normal operation of the range output cathode follower 80. As will be more completely described with reference to FIGURE 3, the range voltage provided over the line 118 may be a fixed range voltage or it may be a variable range voltage depending upon the evaluation mode which is selected by means of the selector unit 1114. The selector unit 114 v is connected into the tire control system and selects any one of 7 separate modes for evaluating the operation of the tire control system. The modes which may be selected by means of the selector unit 114- are first, the positioning of the antenna and the turret in a dead aft position, supplying of a fixed range voltage to the antenna mechanism and the firing of the gun 50 to determine the static error in the alignment of the turret 48 and the gun 50 with the antenna 48, in a manner similar to that described and claimed in the aforementioned co-pending patent application. Two other static modes are provided, in each of which the antenna is positioned in a dead aft position while the turret with its gun 5t)` is positioned 25 mils olf dead aft in elevation and then 2S mils off in azimuth. These two modes provide additional evaluation -information giving a calibration factor of the amount of error in the setting of the turret and the gun with respect to the antenna 48 for 25 mils of movement in both elevation and azimuth. 'I'he other four modes which may b e selected by selector unit 114 are all dynamic modes for dynamically evaluating the operation of the fire control system. These `dynamic modes consist of providing a simulated variable range voltage to simulate a moving target and the operation of the antenna in track from a limited angular position toward dead aft -in four separate directions, that is, either way in azimuth and either way in elevation. Ihus the dynamic operation of the re control system may be evaluated through its entire operating cycle.

Once the armament operator has selected his desired mode of operation he then pushes ring button to start the programmer into operation and to provide the desired dynamic testing of the fire control system. As is shown by dotted lines in FGURE 2 the operation of the selector unit moves a double throw switch 122 which places the ring button 11) in the energization line of programmer 112 and also closes the second pole of the switch from the programmer to the gun 59 whereby when the programmer has reached the proper stage in its operation of the antenna the gun will be fired. The reason for placing the firing button in this type of circuit can be readily understood, since by this method it is necessary for the armament operator to place his finger on the firing button and to hold it down throughout the entire operation of each mode of the evaluator. Thus, if it should become necessary to stop the tiring of the gun 50 before the operation of the evaluator mode is completed, the operator has only to remove his finger from the button 110 and thereby halt the firing of the gun.

The selector unit 114- also throws a two-position switch which connects the gated video signal from range tracking circuit 66 into circuit with recorder 116, through azimuth and elevation discriminators 127. Switch 125 also disconnects error signal circuit 92, allowing the programmer unit 112 to drive antenna 40. The error signal return by the antenna 411 will thus be automatically recorded upon recorder 1116. The recorder also records the filament voltage of the magnetron utilized in the radar unit so that at the end of the evaluation, if there should appear to be some question as to whether the system was operating or not the voltage of the magnetron will be recorded upon the recorder to indicate the state of operation of the radar device.

The operation of the armament flight evaluator device disclosed in FIGURES 2 and 3 will not be described with reference to the iirst 3 modes of operation since they are essentially the same as the automatic aerial harmonization operation which has been described in the aforementioned copending patent application to Allen D. French. Of course, it will be understood that the static errors and calibrate errors obtained from the three static modes are recorded on recorder 116 and are utilized in conjunction with the various dynamic errors to obtain the ovenall evaluation of the fire control system. Briefly, in operating the fire control system in the four evaluating modes, providing dynamic evaluation of the fire control system, the variable range voltage supplied to the range output cathode follower 80 by means of line 118 is used in the closed loop range servo to cause the entire operation of the range tracking system to be focused on this variable range. Additional means are provided for driving the antenna 4@ through the desired tracking angle in either azimuth or elevation, depending upon the position of selector switch 114. This desired angle is fed from programmer 112 over line 124 to the antenna control ampliiier 93 and thence over line 1611 to the antenna drive mechanism 42 which drives the antenna 4d through the desired tracking angle. When the simulated range and tracking angle are at the proper point the gun u is fired, which sends a projectile through the range gate, that is an area in space within the radar beam, which is set up by the variable range voltage on the range output cathode follower 89. The RF pulses reflected back at the time the projectile passes through this r-ange gate are received by antenna `40 and passed on to receiver 62 and the range tracking circuit 66. The gated video error signal from the tracking circuit 66 is fed to the recorder 116, through the switch 125, line 126` and the discriminators 127, Iwhere its azimuth and elevation components are recorded for the necessary evaluation.

Thus the armament flight evaluator device disclosed in FIGURE 2 provides a method for evaluating the over all operation of the fire control system and for providing a permanent record of the operation of such system, which may be utilized in evaluating the system and providing the necessary maintenance and correction to such system.

One form of the electrical connections of the programmer of the armament flight evaluator device of this invention necessary to connect it into the fire control system, as well as the circuitry utilized in the programmer are shown in detail in FIGURE 3. Referring now to FIG- URE 3, the range output cathode follower '86, which is utilized in the lire control system to provide the desired range voltage signal to the closed loop range servo (represented by the range gate generator 68, the early and late signal 72 and 76, and the range tracking circuit 66) is shown as being connected to the programmer unit 112 by lines 1R18 Aand 120; The line 118, when the evaluator is utilized in the four dynamic modes as previously described, .places a variable range voltage on the cathode of the range output cathode follower 30 to simulate a moving target. This voltage is obtained from a positive D.C. voltage source 12S applied to a variable potentiometer 13d, the arm 132 of which is rotated by a motor 134 through gearing 136. A blocking voltage is placed on the grid of the range output cathode follower to prevent its normal operation during evaluation. This voltage is applied to the grid over the line 12d as shown in FIGURE 3, the voltage being derived from a voltage source 133 which is shown as a negative D.-C. voltage source, the desired blocking voltage being obtained by means of a sliding contact 140l on a potentiometer 142 placed across the negative voltage source 133. The variable range signal, which is placed on the cathode of the range output cathode follower Sti, is fed over line 82 and 86 to the computer Sd, as indicated in FIGURE 3, to provide the desired range information to the computer so that the turret 48 and gun 50 (FIGURE 2) will be correctly positioned for the desired range. This variable range voltage is `also fed over lines 82 and S4 to the closed loop range servo, that is the range gate generator 618 and thence over lines 70 and 72 to provide the early gate signal and over line 7i) to delay 74 and line 76 to provide the late gate to the range tracking circuit 66. Thus the desired early and late gate range signals are provided in the range tracking circuit 66 for the variable range of the simulated target.

Also provided in the programmer unit 112 is a control transformer 144 which is connected to either the azimuth or elevation control transformer, indicated at 145, of the antenna y40, depending on the dynamic mode selected by selector unit 1-14. The switching of the selector unit 114 to the desired mode positions the antenna 4) at the limited angular position from which it begins to track the simulated target. As is well known, the rotor of the antenna control transformer 145 (either azimuth or elevation) is excited by a constant excitation voltage, which induces a voltage in the stator thereof, this voltage being applied to the stator of control transformer 144. When the rotor of control transformer 144 is moved, a voltage is induced in the rotor, disturbing the balance between transformers 144 and 145. This voltage, referred to as the angle voltage, is fed over line y146 to the antenna control amplifier 93, causing the antenna to be rotated until the transformers are again balanced. The control transformer 144 is operated by means of a cam 148 and cam follower 150* to provide the desired angle voltage. The cam 148` is driven by motor 134 through gearing 136 in a similar manner to the rotating arm 132 of variable potentiometer 130. The selector unit 114 operates in conjunction with control transformer 144 to provide the desired polarity signal and to determine whether such signal will be utilized in either azimuth or elevation, as will be well understood by those skilled in the art. As indicated in FIGURE 3, as cam 148 rotates it engages a switch i152 closing the switch to thereby fire the gun, when the simulated target is at the range where the gun Slt would be tired at an actual target.

It is thought that the operation of the armament flight evaluator of this invention, in its dynamic modes, will be well understood by the previous detailed description of its circuits and their operation in the evaluator. However, its operation will now be described to insure a clear understanding` of the inventive concept involved in the armament Hight evaluator device of this application. With the equipment installed in the aircraft and connected to the `flight control systemy of such aircraft in the manner indicated previously, and with the aircraft airborne the re control system is turned on. When the fire control system has warmed up, the gunner may then operate the armament flight evaluator whenever desired. For operation of the armament flight evaluator in one of its dynamic modes, the selector unit 114 is placed in the desired dynamic code, for example in azimuth to the left side of the center of the aircraft. When the selector unit 114 has been placed in the desired dynamic mode the evaluator is operated by depressing the firing button 110. This completes a circuit to motor 134 which begins to rotate and through means of gearing 136 rotates the cam 148 and the rotatable arm 132 and potentiometer 130. The rotatable arm 132 moves `from zero to the positive high voltage of potentiometer 130 thereby placing on the cathode of cathode follower the maximum range at lwhich a target would be picked up by the fire control system. rFhis range voltage is fed to the computer 88 which endeavors to position the turret 48 and the gun 50 in a desired position to shoot a projectile to the indicated range. As the arm 132 rotates around potentiometer 131) a decreasing variable range is fed to the cathode of cathode follower S0 and to the computer 8S to constantly reposition the gun Si) in range. This range voltage is also applied to the closed loop range servo to provide the desired early and late `gated voltages to the range tracking circuit 66 as will be well understood to those skilled in the art. At the same time that the potentiometer arm 132 is rotating to constantly provide a decreasing range voltage to the range output cathode follower, the cam 148 is being driven, and through cam follower 1511 drives control transformer 144 to provide the antenna voltage to the antenna control amplifier 98. In the example mentioned the antenna 40 is thus rotated in azimuth from the limit position to the left toward the center line of the aircraft. As the antenna rotates the azimuth angle signals are fed to the computer 88 and thence to the turret 48 and gun Si) to thereby correctly position the turret and gun so as to fire in the direction of the antenna. Thus the turret 48 and gun 50 are constantly positioned in line with a simulated target which. is moving in azimuth from the left of the aircraft and which in range is constantly approaching the aircraft, the target being simulated in angle by the angular voltage from control transformer 144 and in range by the variable range voltage provided to the range output cathode follower 80 from the potentiometer 130. A short time after the motor 134 begins to operate, actually 6.9 seconds after the motor has begun to operate, the cam 148 closes switch 152 thereby tiring the gun. The motor continues to rotate `for approximately more seconds, thus allowing time for the projectiles leaving the gun to pass through the simulated target area and for the echoes to be received back through the antenna, through the receiver 62 and thence over lines 64 to the range tracking circuit 66. The signal from receiver 62 in conjunction with the early .and late gate signals received over lines 72 and lines 76 provides a gated video signal. This gated video signal is transformed into azimuth and elevation components by discriminators 1,27 and fed to recorder I116. Thus there is recorded on recorder unit 116 any error which occurred in the ring of the projectile from the gun 50 towards the simulated target set out by the control transformer 144 and the variable potentiometer 130i. Therefore, any dynamic azimuth or elevation errors which are present in the fire control system through the dynamic operation in azimuth to the left of the center line of the aircraft will be recorded on the recorder unit l116. It will be understood that even though the selected test mode is in azimuth, any .elevation errors, which may be present due to electrical or mechanical errors in the systern, or due to misalignment caused stresses `on the aircraft while in ight, will be recorded during the dynamic azimuth tests. fIn a similar manner, any azimuth errors present during testing in the dynamic elevation modes will also be recorded.

While there has been described hereinbefore the operation of the armament flight evaluator of this invention for the dynamic azimuth operation of the ight control system it will be understood that the same type operation applies tothe azimuth operation to the right of the center line of the aircraft as well as for the elevation operation of the lire control system both above and below the center line of the aircraft. Duri-ng each operation in the particular dynamic mode of the flight control system a permanent record is made on the recorder unit 116 which may be then evaluated by the operator, and by Various personnel including maintenance people, to determine the 10 actual operation of the Hight control system and the necessity of any desired maintenance.

From the above description it can readily be seen that lby this invention there is provided a means for the dynamic evaluation `of a fire control system during dynamic operation of such system under actual flight conditions. Of course, it Will be understood that the various units set forth, the programmer unit 112, the selector unit 114 and the recorder unit 116 may be provided in a number of small light weight units which may be connected to present day iire control systems in any desired manner, being placed within the aircraft in the available spaces. Alternatively, it Will be understood that the device of this invention may be built into iire control systems which are hereafter produced. While there has been shown and described a preferred embodiment of this invention, it will be obvious to those skilled in the art that many variations may be made in the various components described herein, Without departing from the spirit and scope of the invention as defined in the appended claims.

What is 4claimed as new, and which is desired to be secured by Letters Patent of the United States is:

An armament evaluator for use with the fire control system comprising an evaluator device electrically connected with the iire control system, said evaluator device having means for operating the antenna of such system for simulating the tracking of a target, additional means being provided to simulate a variable target range to the range tracking circuitry of the re control system, said evaluator device being designed to lire the gun of the fire control -system when the simulated tanget is at the correct range and position for scoring a hit, and including means for obtaining an indication of the closeness of the path of the fired projectile to the area in space where the simulated target is located, whereby the effectiveness of the re control `system may be evaluated.

References Cited in the ile of this patent UNITED STATES PATENTS 2,409,462 Zworykin et al. Oct. 15, 1946 

